The present invention relates generally to a memory device and, more particularly, to a memory device capable of erasing a sub-sector of memory cells.
Flash memory, which can be electrically erased and reprogrammed, is a type of electrically erasable programmable read-only memory (EEPROM). Since flash memory is non-volatile, no power is needed to retain stored information. In addition, flash memory allows fast read access and large block erasure. These characteristics explain the popularity of flash memory in portable devices such as digital cameras, mobile phones, digital audio players, personal digital assistants (PDAs) and laptop computers.
Flash memory typically stores information in an array of transistors, commonly referred to as “cells,” each of which may store one bit of information. Furthermore, flash memory may be erased in “sectors” or “blocks” having a size of, for example, four megabits or eight megabits. That is, information stored in the memory cells of one sector in a flash memory may be erased in a “flash” at the same time. Despite the advantage of sector or block erasure, however, it may be required in some applications to erase a flash memory in a partial sector or a partial block rather than an entire sector(s) or block(s). It may therefore be desirable to have a memory device with a flexible erasion design that allows partial sector erasure as well as entire sector erasure.